Multi-color one-plate printing method



Feb. 8, 1966 o. D. JOHNSON 3,233,541

MULTI'COLOR ONE-PLATE PRINTING METHOD Filed Jan. 16, 1964 2. Sheets-Sheet 1 INVENTOR.

OLIVER D. JOHNSON Feb. 8, 1966 o. D. JOHNSON 3,233,541

MULTI-COLOR ONE-PLATE PRINTING METHOD Filed Jan. 16, 1964 2 Sheets-Sheet 2 FIG.4

E I I) H. I E E M E E L I 3 1 mm I m I C C C C G I f I l E. F B B B u I 1 l A A A 2 6 O 5 5 6 LIZ: E111:

D- EEILI United States Patent 3,233,541 MULTI-COLOR ONE-PLATE PRINTlNG METHOD Oliver D. Johnson, Vestal, N .Y., assignor to International Business Machines Corporation, New York, N.Y., a

corporation of New York Filed Jan. 16, 1964, Ser. No. 338,211 3 Claims. (Cl. 101-411) This invention relates to a method for producing multi-color prints from a single printing plate, and to printing apparatus adapted to multi-color one-plate printing.

it is the principal object of the invention to provide a method and apparatus that will allow two or more colors to be printed in very close proximity to each other with the registration held to less than 12005. The invention was conceived and developed in connection with the printing of a two-color (red and black) optical test scoring document. This document has the colors aproximately of an inch apart with registration tolerances in both directions of 1-.005".

This requirement is for a machine processable document which not only depends on the position of the colors with respect to each other, but the print quality must also be such that the machine can discriminate between the colors.

Present practice when printing two or more colors very close together is to use a separate print tower for each color. These towers have one inking system for each plate, and registration of different colors is effected by adjusting either the path of the web or by adjusting the plate cylinder.

Running (or length) register is effected by indexing the cylinders or by using compensator rollers. Side register is effected by moving the cylinders with built-in adjusting mechanism. Any errors in bending or mounting the plates, any variations in gears that drive the towers, or any side weave or pulsing of the web will cause a variation in register. The present state of the art of commercial web fed printing equipment does not permit color registration to a tolerance of better than approximately $015".

The method and apparatus herein allows the utilization of present level of printing technology and commercial printing equipment. It also adds certain advantages wh'ch will become clear as the details thereof are described in light of the accompanying drawings. In the drawings, like reference numerals indicate like parts in the several figures, and in these figures:

FIG. 1 is a schematic side elevational representation of an offset press printing unit in combination with three individual inking systems;

FIG. 2 is a developed schematic of the plate dampening system and one roller of each set of form rollers;

FIG. 3 is a schematic representation of certain elements of the press to illustrate the action of the ink as it is carried between the form rollers, the plate, the blan: ket and the paper, only two sets of inking form rollers being represented in the interest of clarity; and

FIG. 4 represents anenlarged fragment of a test score sheet inTegt'trd to which this invention was conceived, and in reference to which it may be explained.

Conventional tests for various aptitudes generally involve multiple choice answers to the several questions 3,233,541 Patented Feb. 8, 1966 which are asked. These answers are represented, respectively, by closely related alphabetically identified spaces such as the spaces 10 in FIGURE 4. The test subject will decide on an answer and it will thereupon mark the corresponding space on the test sheet with a pencil or other writing implement with a stroke sufiiciently dark and bold to permit the scoring machine to recognize the marks. Marks of the nature referred to are indicated in FIG. 4 by the reference numeral 12.

One margin of the test sheet is ordinarily provided with a timing track 14 composed of a plurality of short equally spaced parallel lines 17.

When a test is scored, the marked test sheet is placed in a scoring machine which is adapted to scan and record the several answers 12 under control of the timing marks 17. It can be seen, therefore, that the scoring machine must not only react to the timing marks 17 and to the answer marks 12, but that it must at the same time disregard the other printed matter, such as the answer areas 10. Furthermore, it can be appreciated that the registration of the timing marks 17 and their answer lines 10 must be exact. Moreover, a very close tolerance must be held between the timing marks 17 and the adjacent answer spaces in order to avoid the reading of a timing mark as an answer and vice versa. This is but a single example of multi-color printing which requires close control of registration and tolerances.

The offset press printing unit herein by which the specified registration and tolerances are attained consists of a plate cylinder 16, a blanket cylinder 13 and an impression cylinder 20. These cylinders are geared together in a precise one-to-one speed ratio. The plate cylinder 16 has associated therewith two or more independent inking systems such as the systems A, B and C in PEG. 1.

Conventionally, the inking systems A, B and C each comprises two form rollers 22 and 2-4, three metal vibrating rollers 26, 28 and 30, four rubber composition intermediate rollers 32, 34, 36 and 33, a drum 4%) which may also be a vibrator, a ductor roller 2, a fountain roller 44, and an ink fountain 46. The form rollers in the inking systems B and C corresponding to the form rollers 22 and 24 of the inking system A are, respectively, marked 48, 5t), 52 and 54. The fountain and ductor roller meter the ink into the inking system. The vibrator rollers, the intermediate rollers, and the drum are of various diameters so as to distribute the ink evenly in their running direction and prevent streaking. The vibrator rollers provide crosswise (lateral) distribution, preventing r-idging of the ink and reduce the inks tendencies to fly or mist.

The press may employ a conventional dampening system or a Dahlgren dampening system. In FIG. 1, a conventional dampening system is adapted to employ a dampening solution directly to the plate cylinder 1-6. This system consists of a pair of dampening rollers 56 and 58, a metallic vibrator or distributing roller 60, a ductor roller 62, a fountain roller 64, and a water fountain 66.

If a Dah-lgren dampening system is employed, it will be located in proximity to and it will operate in connection with the first form roller of the train A. In FIG. 1, a Dahlgren dampening system (in dotted lines) comprising a Water fountain 68, a fountain roller and a hydrophyli-c transfer roller 72 is associated with the form roller 22 of the inking system A. Therein the hydro-pholic roller transfer'72 applies moisture to the form roller 22.

The printing plate carried by the plate cylinder 16 is conventionally a planographic plate, i.e., its image and nonimage areas are substantially at the same level. The image areas are ink-receptive areas surrounded by waterreceptive non-image areas. When moistened, the waterreceptive areas refuse to take the ink while the image areas accept the ink but repel the water.

The blanket cylinder 18 derives its name from the printing blanket which is adapted to cover the cylinder. A conventional blanket consists of plies of lOng cotton fabric calen-dered together with a special rubber cement and then coated with a rubber compound on one side. The thickness of the rubber skim-coat varies on different makes but an overall average thickness of is common.

The printing cycle consist in (1) dampening the nonimage areas on the plate cylinder 16; (2) inking the image areas; and (3) transferring ink from the image areas of the plate cylinder 16 to the blanket it; from which it is offset to the paper web 72, or the like, which is threaded between the blanket cylinder 13 and the impression cylinder 20.

As seen in FIG. 2, the form roller 22 (representative also of its com anion roller 24) extends across the entire width of the plate cylinder 16 and it is employed to apply the first selected ink to the entire image on the plate cylinder. The first selected ink would most usually be the lightest colored ink. If a Dahlgren dampening system is employed, it will be operated against the first form roller 22. If a conventional dampening system is applied, it will be inserted ahead of the first form roller 22. Applications of the invention may arise wherein it may be desirable for each ink train to have a seperate dampening system.

The form rollers of the inking system B are designed to apply to the image the next ink, and these rollers are cut away as indicated at 74 of FIG. 2 to a reduced diameter throughout a portion of their length, such that this set of form rollers has an effective contact with the plate cylinder across only a partial width thereof, and the set does not contact the plate cylinder where the effect of the first applied ink is desired. In the area 74a, where the rollers 48 and it) (represented in MG. 2 by the rollers 48) are not cut away, the ink of the ink train B will cover or overlay the first ink applied to the image by the form rollers 22 and 24.

The form rollers 52 and 54 of ink train C are adapted to apply a third ink to the image of the plate cylinder 16. The rollers 52 and as shown by the roller 52 in FIG. 2, which is also representative of its companion roller 54, are reduced in diameter as at 76 to remove this area of the rollers from contact with adjacent rollers and thereby render the reduced diameter incapable of transferring ink. The area 76a, however, is an effective element of the ink train for the application 'of the third ink to the desired area at the printing image on the plate cylinder lid.

The action of the ink as it is carried between the form rollers, the plate, the blanket, and the paper can be seen by reference to FIG. 3. In this figure, the inking system B has been omitted for the purpose of clarity. In FIG. 3, the image has had the initial ink 78 applied thereto by the form rollers 22 and 24. The form rollers 52 and 54 apply the second ink 8(1 to selected parts of the image. As the image passes the nip of the plate cylinder and the blanket cylinder, most of the second ink is split off and is deposited on the blanket 1-8, with the underlying first ink remaining on the plate 16, as shown at 78a. In the meanwhile, the first ink 7 8 exposed at the face of the plate 16 is also transferred to the blanket 13, as shown at 7812. The blanket carries both the first ink and the second ink to the Web 72. It should be noted that if any of the first ink has been pulled off the plate by the blanket during the splitting of the ink, it will be disposed next to the web 72 with the second ink covering it. A very thin film of ink is normally left on the blanket after the web has been imprinted. Normal high quality offset-inks mix very little at contiguous surfaces and give satisfactory results when used with the present invention. This is so partly because of the very short time that compound ink layers are upon plate cylinder 16 before being split off, and partly because the very thin layers of ink cannot circulate. There is thus too little time for osmosis-type mixing, and no room for circulation-type mixing. Different standard offset-inks will be employed depending upon this time and other operating conditions.

With the ink form being split in the manner stated, very little, if any, of the darker colored inks are carried into the lighter colored inking systems. This result is due to the fact that all ink trains are being supplied from the fountain to the ink rollers and then the ink is removed from the blanket by the web. This shouldalways cause the ink fiow to be from the ink rollers to the plate, to the blanket, and to the paper, thereby minimizing any tendericies to feed back and mix.

With the above-described method and apparatus, colors can be printed very close to each other with the only variations in register being the variation inherent in the printing plate itself. By resort to known instruments and techniques for the preparation of copy, this variation can be held to :002" or less.

The foregoing shows that the multi-color one-plate printing method herein is composed of the steps to apply a first coat of ink to an entire printing image, therefore, superimposing a second coat of ink over portion-s only of the inked image, splitting the second coat of ink from the first applied undercoat of ink and simultaneously transferring the split-off coat and the first applied ink from the remainder of the image to a transfer surface, and finally forming a printing impression with the ink so tranferred.

Moreover, it is shown that the apparatus for the practical performance of the method is very simple in its nature, comprising, as it does, independent first and second ink trains operating in conjunction with a single plate, each train having its own ink fountain; at least one form roller for each train, and in which a form roller of the first ink train is so formed as to apply one ink to the entire printing image while the form roller of the second ink train is so formed as to superimpose a second ink of different color on the first applied ink in selected portions of the printing image.

The invention has been illustrated and described in a single embodiment. The e sence of the invention may be enjoyed, however, even though additional steps are added to the method, and resort is had to equivalent or even different instruments for performing the same. Variations in and equivalent structures of the illustrated and described printing apparatus are also contemplated by the terms of the following claims.

What is claimed is:

1. The method of producing multi-color prints from a single plate which comprises the steps of applying a first coat of ink to an entire printing image, thereafter superimposing a second coat of ink over portions only of said printing image, splitting said second coat of ink from said first applied under-coat of ink and simultaneously transferring said split-off coat and said first applied coat from the remainder of said image to a transfer surface so that said coats are turned upside down thereon, and finally applying said so transferred coats so as to form a printed impression wherein said coats are turned right side up again.

2. The method of producing multi-color prints from a single plate which comprises the steps of applying a first coat of light colored ink to an entire printed image, thereafter superimposing a second coat of ink of a darker color over portions only of said inked image, splitting said darker ink from said lighter first applied undercoat of ink and simultaneously transferring said darker split-off coat and said first applied'lighter coat from the remainder of said image to a transfer surface so that said coats are turned upside down thereon, and finally applying said so transferred coats so as to form a printed impression wherein said coats are turned right side up again.

3. The method of producing multi-color prints from a single plate which comprises the steps of applying a first coat of light colored ink to an entire printing image, thereafter successively superimposing inks of a progressively darker color over successively diminishing portions of said inked surface to form areas on said image having two or more ink layers thereon with the darkest of said inks in each case forming the surface coat, splitting said surface coats of ink from their immediate undercoat and simultaneously transferring said split-oflf coats and said first applied coat of the remainder of said image to a transfer surface so that said coats are turned upside down thereon, and finally applying said so transferred coats so as to form a printed impression wherein said coats are turned right side up again.

References Cited by the Examiner UNITED STATES PATENTS 546,024 9/1895 Morrison 101-2 11 X 565,891 8/1896 Frauenfe lder 101211 896,733 8/1908 Knapp 101-211 1,260,824- 3/1918 Smith 1D1-211 2,894,453 7/1959 Trisler 101148 X 3,103,880 9/1163 Sanford et al. 101-136 FOREIGN PATENTS 334,183 8/ 1930 Great Britain.

EUGENE R. CAP OZIO, Primary Examiner. 

1. THE METHOD OF PRODUCING MULTI-COLOR PRINTS FROM A SINGLE PLATE WHICH COMPRISES THE STEPS OF APPLYING A FIRST COAT OF INK TO AN ENTIRE PRINTING IMAGE, THEREAFTER SUPERIMPOSING A SECOND COAT OF INK OVER PORTIONS ONLY OF SAID PRINTING IMAGE, SPLITTING SAID SECOND COAT OF INK FROM SAID FIRST APPLIED UNDERCOAT OF INK AND SIMULTANEOUSLY TRANSFERRING SAID SPLIT-OFF COAT AND SAID FIRST APPLIED COAT FROM THE REMAINDER OF SAID IMAGE TO A TRANSFER SURFACE SO THAT SAID COATS ARE TURNED UPSIDE DOWN THEREON, AND FINALLY APPLYING SAID SO TRANSFERRED COATS SO AS TO FORM A PRINTED IMPRESSION WHEREIN SAID COATS ARE TURNED RIGHT SIDE UP AGAIN. 